<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
            .father {
            position: relative;
            width: 200px;
            height: 200px;
            background-color: pink;
            margin: 0 auto;
            text-align: center;
            transform: matrix(1, 0, 0, 1, 0, 0);
            }
            .father:hover{
                transition: all 2s;
                transform:rotateY(180deg);
            }
            .up{
                position: absolute;
                top: 0;
                left: 0;
                background-color: orange;
                border-radius: 50%;
                width: 100px;
                height: 100px;
            }
    </style>
</head>
<body>
    
    <div class="father">
        <div class="up">恭喜发财</div>
        <div class="down"></div>
    </div>

</body>
</html>